Images are instantly rendered to the browser when properly sent on the chat, however if you send a oneboxed image, it will not render as it would normally.
For instance the below will work as expected:
http://site/image_with_proper_file_extension
While this one:
[http://site/image_with_proper_file_extension](http://site/some_other_link/)
Or this one:
[![description](http://site/image_with_proper_file_extension)](http://site/some_other_link/)
Or this one:
[![description][1]](http://site/some_other_link/) [1] http://site/image_with_proper_file_extension
Will show you the image link rather than an image. The link will be shown as expected regardless, at least on the first example.
Sample image working: